President Joko Widodo's abruptly cancelled trip to Sydney, due to violence in Jakarta, would have been the first bilateral visit by an Indonesian president to Australia since 2010. This does not signal a snub, or reversal from the steady upward trend since the lows of executions, boat "turn-backs" and Snowden. But it highlights how rare such opportunities are, and how Canberra struggles to capture attention in Jakarta's rear-view mirror. Until things go awry.

Although bilateral military ties are in positive shape overall, prospects for Australia and Indonesia maritime co-operation in the South China Sea are on a similar course for disappointment. Expectations were raised last week following the "2+2" conclave of foreign and defence ministers in Bali, at which Defence Minister Ryamizard Ryacudu was reported to have raised the possibility of joint "peace patrols" in either the South China Sea or Sulu Sea. That much was confirmed in separate statements from Defence Minister Marise Payne and Foreign Minister Julie Bishop. This may have added inadvertently to speculation that a steep change in bilateral maritime activities "consistent with our policy of exercising our right of freedom of navigation" was brewing.

Australia tries consistently to do more with Indonesia's navy. But the foreign ministry has continually rebuffed Canberra's proposals to expand co-ordinated patrols within the navy's western command area of responsibility, on grounds that not all maritime boundaries are settled and given Jakarta's continuing, if waning, opposition to Australia's turn-back policy.

Indonesia's naval high command is broadly receptive to co-operating with Australia, but the western fleet itself is more cautious about expanding naval engagement. It fears this could strain capacity in busy shipping lanes, and cut across turf furrows with civilian maritime law-enforcement agencies. The reality is that Jakarta has no maritime co-operation strategy with Australia.

While the northern regency of Natuna falls within the western command's area, it is understood that joint patrols were not specifically discussed in relation to the South China Sea, at Bali. This confusion arose from Ryacudu's separate press conference without the Foreign Minister present. There is no agreed policy basis for this in Jakarta.

Indonesia's appetite for expanding maritime patrols thus appears limited. However, Jakarta has lost some of its previous reticence towards law-enforcement co-operation with regional navies since a high-profile hostage-taking case in the Sulu Sea earlier this year. Australia could conceivably participate in three-way Philippine-Indonesia-Malaysia patrols there in future, though its role would probably be indirect and requires more than an invitation from Jakarta.

The format and location for bilateral naval exercises are less constrained. This holds out more flexible potential for the two defence forces to co-operate - as suggested by Indonesia's enthusiastic participation at the recent Kakadu (naval) and Pitch Black (air) drills in northern Australia. Air force links are currently strongest.

One possibility is to stage Exercise Cassowary off Natuna in future, framed within a law-enforcement, anti-illegal fishing context. Despite upgrades announced by Jokowi, infrastructure on the islands remains basic. This would therefore require Australia's navy to bear the logistical burden of supporting the exercise, although that accords with the prevailing emphasis on fleet concentration and sea-basing concepts. Australia could also help to direct regional maritime domain awareness capacity-building efforts to Natuna. Hosting exercise New Horizon, a higher-intensity bilateral naval drill, in the South China Sea might be a longer-term aspiration. But threat perceptions towards China would need to intensify on both sides first.

Joint activities of any kind in the South China Sea are speculative and practically some way off. Widodo is invariably uncompromising on Indonesian sovereignty, but that should not be taken for a willingness to partake in joint activities with Australia, especially as a means of concerted signalling towards China. Like other leaders in the region, he views Beijing also as an economic opportunity. China is now Indonesia's third-largest source of foreign direct investment, which has more than doubled since 2015. To the extent China raised Indonesian hackles in the South China Sea by poaching within waters off Natuna earlier this year, Jakarta's response has been effectively corralled down bilateral lines. That works to Beijing's advantage.

Disappointment at the scrubbed Australia-Indonesia summit will shortly be forgotten in the melodrama of the US presidential election and aftermath. Whoever triumphs, whether the US-Australia alliance waxes or wanes, South-east Asia's importance to Australia's wellbeing and security will only grow. Despite repeated false dawns and premature sunsets, our relationship with Indonesia holds the key to the region - the more so given Malaysia and the Philippines' recent "wobbliness".

Deferring to Indonesia's sovereignty sensitivities and negotiating its sclerotic internal turf boundaries is frustrating. Canberra should not have to be the perpetually over-eager suitor in a relationship too often defined by false starts. But at this acute geopolitical juncture in south-east Asia, the baseline priority for Canberra's defence diplomacy should be to demonstrate common purpose with Indonesia, even if this means proceeding at a slower pace. That's not to say that other opportunities should not be explored, including through the Five Power Defence Arrangements, but on many maritime activities Indonesia's neighbours are likely to defer to Jakarta anyway.